Some experience and lessons of performance optimization

1: Do not log4j1 log, because the log file when logging, will scramble for locks, resulting in thread blocking, using LOG4J2, and to use its asynchronous way;

2: Memory-based services, generally use map to save data, so when updating data, if it is a large number of updates, it is best not to use the object completely replace the way, because in this case, the old object programming garbage, will lead to the old age of recycling, produce full GC, preferably only updated field information changed So the new object will be recycled in the young GC without the full GC being generated;

3: